Recently, there has been some controversy about the results of two papers,
one by Liu and Parr [Chem. Phys. Lett. 278, 341 (1997)] and one by Nesbet [
Phys. Rev. A 58, R12 (1998)]. It is pointed out that the two problems have
the same origin, which is the fact that the wave-functidn-density-wave-func
tion mapping in density-functional theory is not an identity.